The invention relates to a coagulating/condensing device and method capable of precipitating fine particles at exceedingly higher velocities than natural settling velocity, without the use of any condensing agent, from thin contaminated liquids, while making use of electrolyte in the contaminated liquids as a condensing agent, and growing the fine particles further from mass-floc (giant floc) to coagulate and separate the liquids into highly rich sludge and a clear liquid.
Conventionally, a straight pipe has been used for a flocculating pipe (referred to a double pipe, in which two liquids in an injecting pipe and a mixing pipe are brought into laminar contact with each other). The longer the flocculating pipe, the higher it is in a treating capability (flocculating capability). The pipe involves many restrictions when many pipes having a length over several meters are to be installed in a site in order to treat a large quantity of a liquid, and has a disadvantage that an increase in installation cost is incurred when short flocculating pipes of increased number are used to provide the restrictions.
The inventors of this application have proposed (Japanese Patent Examined Publication Nos. 16563/1995 and 29119/1995) a coagulation apparatus and method for coagulating and separating fine particles [microorganism (activated sludge), algal, inorganic substance, plankton and so on] from a water being treated, containing fine particles and including brewery effluent, cultured growth liquids, dredge water and the like. To coagulate fine particles in an injected liquid and a water being treated (dredge water) in the coagulation apparatus, it is absolutely conditional to bring into laminar contact with each other two liquids different in electrolyte concentration (potential difference). That is, to effect laminar contact, a flow rate of a liquid being treated and supplied to a single mixing tube must be maintained at Re less than 105. Further, while the throughput is enhanced by causing a liquid being treated and a floc-containing liquid in the mixing tube to collide and mix with each other, a further enhancement of concentration of flocculated and concentrated sludge and miniaturization of an associated coagulating/condensing device have been desired in installing the coagulating/condensing device in existing solid-liquid separation sections.
Conventionally, a straight pipe has been used for a flocculating pipe (referred to a double pipe, in which two liquids in an injecting pipe and a mixing pipe are brought into laminar contact with each other). The longer the flocculating pipe, the higher it in a treating capability (flocculating capability). The pipe involves many restrictions when may pipes having a length over several meters are to be installed in a site in order to treat a large quantity of a liquid, and has a disadvantage that an increase in installation cost is incurred when short flocculating pipes of increased number are used to accommodate for such restrictions.
The longer (for example, over 4 meters) the flocculating pipe, the higher it is in treating capability, but irregularities, such as welding or the like, on connections are not allowable in obtaining a laminar flow, many restrictions on installation of an apparatus are involved, it takes many days to complete construction, and the apparatus is not easy to move and so lacks mobility. Hereupon, miniaturization enabling installation on a conveying vehicle while maintaining the flocculating capability has been highly demanded, and so a coagulating/condensing device coming in a range of existing solid-liquid separation sections has been a most important issue.
In such apparatus, a difference in electrolyte concentration between two liquids, that is, an injected liquid and a mixed liquid in a flocculating pipe is adjusted to be at least 0.1 mg/liter, the two liquids are brought into laminar contact with each other to maintain a difference of at least 0.1 mV in surface potential between fine particles of the two liquids at liquid interface and a concentration of pollution is continuously maintained to keep a distance between particles of the two liquids within 100 xc3x85 (angstrom), which causes collision and flocculation to form floc in a moment. However, there is a disadvantage that flocculation will not result when the apparatus undergoes minute vibrations or the like to break a laminar interface between the two liquids, resulting in mixing of the two liquids. Therefore, it is an inevitable problem in outdoor apparatuses to prevent vibrations of a lengthy flocculating pipe.
Conventionally, there has been involved a disadvantage that floc taken out from an overflow weir of a floc forming tank in a manner of straight pipe or sloped plate is excessively giant (30 to 40 mm) to be great in fall velocity to cause a great resistance between it and a stagnant water to produce many small particles peeling off the giant floc falling down the sloped plate, and when the giant floc begins to fall down the sloped plate, a clean liquid in a floc forming tank is suddenly made pollutant by such peeled-off particles rising in a gap between wall of the floc forming tank and the sloped plate, and the concentrating capability in a bottom of the solid-liquid separation unit is degraded at the same time. An apparatus intended for flocculating separation for obtaining a clean liquid needs a system for continuously treating such peeled-off particles and a device for prevention of peeling-off on the sloped plate.
With the above-mentioned Japanese Patent Examined Publication Nos. 16563/1995 and 29119/1995, floc formed in a mixing pipe collides with pollutant fine particles within a floc forming tank to produce a mass-floc, and there are involved restrictions that an injected liquid and a mixed liquid be made to perform laminar contact. Since a quantity of a liquid containing therein floc in a treated liquid per a flocculating pipe, which is straight, is small, a mass-floc is formed within the floc forming tank even when a liquid being treated is increased to three to three hundreds of times the liquid containing therein floc from the flocculating pipe for the purpose of treating a large quantity of a liquid being treated, but peeling-off of small particles from floc surfaces is violently caused when floc becomes 35 mm or more in diameter during falling and transferring of the mass-floc to the solid-liquid separation unit through the sloped plate. Accordingly, a demand has been made for development of a means for tranferring in a state of less peeling-off a giant floc produced upon collision and mixing of the floc with a liquid being treated, 10 to 50 times or more a liquid containing therein floc, and for a method capable of increasing a liquid being treated, to 10 to 50 times or more a liquid containing therein floc. Also, miniaturization enabling installation on a vehicle has been highly demanded, and further a coagulating/condensing device coming in a range of existing solid-liquid separation sections has been a most important issue.
In a papermaking process in paper manufacturing, a large quantity of a flocculating agent is used in flocculating a large quantity of waste water (referred to as a thin contaminated liquid) containing thin fine fiber particles below a screen. So, a demand has been made for a coagulating/condensing device and a coagulating/condensing method for performing a flocculating treatment without the use of a flocculating agent in flocculating a large quantity of thin contaminated liquid.
Since any flocculating agent cannot be used in precipitation in a washing (harshness removing) process of food materials from thick fine particles, concern is felt for precipitation. So, a demand has been made for development of a coagulating/condensing device and a coagulating/condensing method, any flocculating agent is not used, a time for the washing process is shortened, and a yield rate is high in the washing process. In particular, it is necessary to develop a solid-liquid separation device for removing a major part of a liquid by means of an inexpensive coagulating/condensing device before an expensive device is used in filtration and deliquoring in a process of separating fine particles and a large quantity of liquid from each other.
A coagulating/condensing device and a coagulating/condensing method, which the inventors of this application make an object of the invention, involve a maximum disadvantage that a mass-floc cannot be formed, even when a liquid being treated is supplied, in the case where a floc-containing liquid is not present, in which floc is formed by laminar contact of an injected liquid and a mixed liquid. So, floc is not formed when either of the two liquids is not supplied into a mixing pipe, with the result that a non-flocculated contaminated liquid is discharged to public water. Most waste water treatment apparatuses run in unattended operation at night, and a demand has been made for a coagulating/condensing device and a coagulating/condensing method, by which the above-mentioned problem is solved.
The inventors of this application have solved the above-mentioned problem in technology in a coagulating/condensing device and a coagulating/condensing method by providing a coagulating/condensing device and a coagulating/condensing method described in the following items (1) to (8), and enabled concentration and separation of a water being treated, into a high-concentration sludge and a clean liquid, and miniaturization enabling installation on a vehicle.
(1) A coagulating/condensing device for causing liquids at different electric potentials containing fine particles to flow down through inner and outer pipes, respectively, of a multiple pipe and for causing liquids in the inner and outer pipes to contact with each other downstream to make fine particle floc, the device comprising a spiral coagulating pipe composed of a spiral mixing pipe formed by the inner and outer pipes of the multiple pipe, the inner pipe having an opening thereof formed in the outer pipe to face downstream, solid being made floc by causing liquids at different electric potentials separately supplied from the inner and outer pipes to contact with each other.
In addition, the term xe2x80x9cspiralxe2x80x9d used in this application generally refers to arcuate, spiral, coil or the like, which involve bending. A liquid supplied flows down in a planar manner or with a difference in level while following an entire circumference of a spiral circle or the same several times or a part of the same.
(2) A coagulating/condensing device comprising a liquid supplying unit for supplying a liquid being treated containing fine particles, and a solid-liquid separation unit disposed in a lower position than the liquid supplying unit, the liquid supplying unit comprising a delivering chamber for delivering a liquid being treated, and a liquid dispersing chamber, and wherein a spiral mixing pipe for permitting a liquid from the liquid dispersing chamber to flow down therethrough, and an amount increasing pipe for supplying from the delivering chamber a liquid being treated join together at a merging portion disposed downstream, a spiral injection pipe with an opening facing downstream is provided in the spiral mixing pipe, two liquids at different electric potentials supplied separately to the spiral mixing pipe and the spiral injection pipe are caused to contact with each other at the opening to form a floc-containing liquid, and the floc-containing liquid is further made to mix with the liquid being treated at the merging portion downstream of the amount increasing pipe to form a mass-floc. (3) This embodiment of the device further includes a colliding/mixing unit provided in the vicinity of a portion where an end of the mixing pipe having therein an opening of an end of the injection pipe merges with a liquid, which flows down through the amount increasing pipe.
The colliding/mixing unit referred to here suffices to be a construction having a function of equalizing floc in diameter and preventing formation of fat floc (35 mm or more), which is liable to peel off upon collision with a liquid being treated, and can be typified by a construction, in which a plurality of nozzles and orifice perforated plates are alternately combined with each other to be provided in a mixing pipe, and which equalizes floc in diameter by repeated collision and dispersion.
(4) A coagulating/condensing device composed of a solid-liquid separation unit and a delivering chamber and a liquid dispersing chamber, both of which are disposed above the solid-liquid separation unit, and further comprising a spiral mixing pipe provided in a spiral amount increasing pipe extended from the delivering chamber for permitting a liquid from the liquid dispersing chamber to flow down therethrough, and a spiral injection pipe provided inside the spiral mixing pipe and having an opening facing downstream, and wherein the spiral amount increasing pipe, the spiral mixing pipe and the spiral injection pipe constitute a spiral triple pipe, and two liquids at different electric potentials supplied separately to the spiral mixing pipe and the spiral injection pipe are caused to contact with each other at the opening to be made a floc-containing liquid, which further mixes with the liquid being treated at the merging portion downstream of the amount increasing pipe to be made a mass-floc.
(5) This embodiment of the device further includes a bracket for supporting the injection pipe or the mixing pipe within the mixing pipe or the amount increasing pipe in a coaxial manner. The bracket includes a plurality of vane portions, which are contacted with and supported by the pipe inner wall at predetermined intervals with the vane portions being sharpened at an upstream or downstream side thereof to reduce flow resistance.
(6) A coagulating/condensing device composed of a delivering chamber and a liquid dispersing chamber, both of which are disposed above a solid-liquid separation unit, and further comprising a spiral mixing pipe for permitting a liquid from the liquid dispersing chamber to flow down therethrough, the spiral mixing pipe being made to merge on a downstream side with a spiral amount increasing pipe extended from the delivering chamber, a spiral injection pipe provided inside the spiral mixing pipe to be opened in a downstream direction, a floc forming tank provided to have a lower portion thereof closed and disposed in the solid-liquid separation unit, the spiral amount increasing pipe having an end thereof disposed inside the floc forming tank, and a spiral down comer provided outside or inside the floc forming tank and having an end thereof opened to the solid-liquid separation unit.
(7) A coagulating/condensing device composed of a delivering chamber and a liquid dispersing chamber, both of which are disposed above a solid-liquid separation unit, and further comprising a plurality of spiral mixing pipes for permitting a liquid from the liquid dispersing chamber to flow down therethrough, the plurality of spiral mixing pipes being made to merge on a downstream side with a plurality of spiral amount increasing pipes extended from the delivering chamber, or the plurality of spiral mixing pipes being provided in the plurality of spiral amount increasing pipes to constitute multiple pipes, spiral injection pipes provided inside the respective spiral mixing pipes to be opened in a downstream direction, a floc forming tank provided to have a lower portion thereof closed and disposed in the solid-liquid separation unit, the plurality of spiral amount increasing pipes having ends thereof disposed inside the floc forming tank, and a spiral down comer provided extended from the floc forming tank.
(8) A coagulating/condensing method comprising the steps of: causing an injected liquid and a scattered liquid, both of which are at different electric potentials, to flow down by way of a mixing pipe composed of an outer pipe and an inner pipe, each of which is formed in a spiral configuration, bringing the liquids into contact with each other on a downstream side to make a floc-containing liquid, and mixing the floc-containing liquid with a liquid being treated containing therein fine particles, to form mass-floc to thereby perform solid-liquid separation.